Moving enclosures for laser equipment

ABSTRACT

Moving enclosures for laser equipment are provided. A machine tool installation is disclosed including (a) a laser cutting head configured to be movable in three dimensions; (b) a workpiece support configured to support a workpiece in operative relationship with the laser cutting head (c) a skirt configured to surround the laser cutting head on three sides and intercept light that passes from the head and is reflected off of the workpiece or workpiece support; and (d) a protective cover positioned to intercept light that is reflected off of the workpiece or workpiece support and is not intercepted by the skirt. The skirt and protective cover are configured to move laterally with the laser cutting head.

TECHNICAL FIELD

This invention relates to moving enclosures for laser equipment, toprotect operators from uncontrolled beam reflection during laseroperation.

BACKGROUND

It is important to protect operators working around laser equipment,e.g., equipment for laser cutting of workpieces, from uncontrolled beamreflection during laser operation. Such reflection, which can occur forexample while a part that is being cut by a laser is tipped, couldinjure the operator if it contacts the operator's body. It is alsoimportant, however, that the operator have easy access to parts of theequipment that need to be changed or maintained, for example the cuttinghead, when the laser is not operating.

In some cases, for example as disclosed in U.S. Pat. No. 6,987,241, theequipment may be enclosed in a stationary cabin-like enclosure that isaccessed through sliding doors.

SUMMARY

The disclosure features enclosures for laser equipment that are movableand that allow easy access to a cutting head of the laser equipmentwhile providing effective safety protection when the laser is inoperation.

In one aspect, the present disclosure features a machine toolinstallation comprising: (a) a laser cutting head configured to bemovable in at least two dimensions; (b) a workpiece support configuredto support a workpiece in operative relationship with the laser cuttinghead; (c) a skirt configured to surround the laser cutting head on threesides and intercept light that passes from the head and is reflected offof the workpiece or workpiece support; and (d) a protective coverpositioned to intercept light that is reflected off of the workpiece orworkpiece support and is not intercepted by the skirt; the skirt andprotective cover being configured to move laterally with the lasercutting head.

Some implementations may include one or more of the following features.The skirt may be configured to move vertically with the cutting head, oralternatively, the skirt may be configured to move verticallyindependently of the cutting head. In the latter case, the machine toolinstallation may include a skirt drive motor and a cam arrangementconfigured to raise and lower the skirt in response to input from theskirt drive motor. The machine tool installation may also include acontroller configured to control the vertical height of the skirt, and aheight regulation device comprising a sensor configured to detect thevertical position of the workpiece and transmit a signal to thecontroller.

The skirt may be configured to move horizontally, in a second directionorthogonal to the lateral movement, with the laser cutting head. Theskirt may be configured to move within the protective cover, which insome implementations is not configured for movement in the seconddirection. The skirt may include an array of pins mounted on asubstantially U-shaped bracket. The pins may be arranged in a labyrinth,with their long axes extending generally parallel to the direction oflight emitted by the laser cutting head.

The protective cover may include a door, and may define open side andback regions. The machine tool installation may also include a motiondevice configured to move the protective cover and laser cutting headlaterally. In some cases, the machine tool installation also includes asupport structure from which the protective cover and laser cutting headare cantilevered and along which the protective cover and laser cuttinghead move laterally. Alternatively, the machine tool installation mayinclude a pair of opposed rails between which the motion device ismounted and along which the motion device, protective cover and lasercutting head move laterally. In the latter case, the protective covermay in some cases be mounted directly on the laser cutting head.

In another aspect, the disclosure features a moving enclosure for amachine tool installation including a laser cutting head configured tobe movable in at least two dimensions, the enclosure comprising: (a) askirt configured to surround the laser cutting head on three sides; (b)a z-axis motion control unit, on which the skirt is mounted, configuredto position the skirt vertically relative to a workpiece to be machined;and (c) a protective cover positioned to intercept reflected light fromthe laser cutting head that is not intercepted by the skirt; the skirtand protective cover being configured to move laterally with the lasercutting head.

The disclosure also features methods of protecting operators of machinetool installations from laser light using the moving enclosuresdisclosed herein. The details of one or more implementations are setforth in the accompanying drawings and the description below. Otherfeatures and advantages of the enclosures disclosed herein will beapparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a laser machine tool installationincluding a moving enclosure according to one implementation.

FIG. 2 is a front view of the moving enclosure shown in FIG. 1

FIGS. 3 and 4 are front and bottom views, respectively, of a skirtportion of the moving enclosure shown in FIG. 1.

FIG. 5 is a view of the moving enclosure shown in FIG. 1 taken frombelow.

FIG. 6 is a side cross-sectional view of the moving enclosure shown inFIG. 1.

FIG. 7 is a side view of a spring mounted pin used in the skirt portionshown in FIGS. 3 and 4.

FIG. 8 is a front view of the skirt portion of a moving enclosureaccording to an alternative embodiment.

FIG. 9 is a top view of a moving enclosure according to an alternativeimplementation.

DETAILED DESCRIPTION

Referring to FIG. 1, a laser machine tool installation 10 includes amoving enclosure 11 that surrounds a laser cutting head 8 (FIG. 2), aworkpiece bed 2 including a plurality of workpiece supports 3 andsub-supports 4 disposed orthogonal to the supports 3. The workpiecesupports 3 are configured to support a workpiece (not shown), e.g., asheet of metal, beneath the laser cutting head during a cuttingoperation. The moving enclosure 11 protects the operator from laserlight reflected off of the workpiece supports, sub-supports orworkpiece, as will be discussed in detail below. The installation 10also includes material transfer units 5, 6, configured to place theworkpiece on the workpiece bed prior to processing and remove it fromthe bed after processing.

The moving enclosure 11 includes a protective cover 14 having aprotective door 12, e.g., a bifold door. In the implementation shown inFIG. 1, the laser cutting head 8 and the protective cover 14 arecantilevered out from a rear support surface 100 of the installation 10,and are mounted on a motion unit 13. The motion unit 13 includes a motor(not shown) that moves the laser cutting head horizontally in the xdirection. The cutting head moves in the y direction along y-directionguides (not shown), and in the z direction on z-direction guidesinstalled on a z-axis plate 120 (FIG. 3). The laser cutting head movesrelative to the protective cover 14 in the y direction (towards and awayfrom the protective door 12), and the z direction (up and down withinthe protective cover), and with the protective cover in the x direction(laterally). In the x direction, the protective cover and laser cuttinghead travel along the support surface 100. Motion of the head and coverin the x direction allows the laser cutting head and protective cover tomove out of the way during placement and removal of a workpiece by thematerial transfer units, and allows the cutting head to make cuts in thex direction when it is in operation. Motion of the head in the ydirection within the protective cover allows the cutting head to makecuts in the y direction, while motion of the head in the z directionallows the distance between the cutting head and the workpiece to beadjusted, e.g., to compensate for different workpiece thicknesses and/orto utilize different processing techniques.

During cutting, it is important that the operator of the machine toolinstallation 10 be protected from stray laser light that may reflect offof the workpiece, the workpiece supports 3, or the sub-supports 4. Theprotective door 12 protects the operator from stray laser beams that aredirected towards the front (door side) of the cover 14, while allowingthe operator to access the laser cutting head within the enclosure 11,e.g., to change the head.

In order to minimize the weight of the protective cover 14 and allow itto be easily moved in the x direction, and avoid collisions with cutparts, the protective cover 14 is open in regions 20, 22 along its sidesand also is open at the back. Thus, a secondary device is needed toprotect the operator from reflected laser beams in these areas. Toprovide this protection, the moving enclosure 11 further includes askirt 28 (FIGS. 3-4) that surrounds the laser cutting head on threesides 30, 32 and 34, corresponding to the open side and back regions ofthe protective cover. The skirt 28 is open at the front (front opening7, FIG. 5), allowing the operator to easily access the laser cuttinghead 8 when the protective door 12 is open.

Referring to FIG. 5, which shows the laser cutting head 8 from thebottom, the skirt 28 is designed so that when the laser cutting head 8is in its position furthest from the protective door 12 in the ydirection, reflected laser light could escape from the open front 7 ofthe skirt at any point within angle A. The width W of door 12 ispreferably selected to cover the entire area into which the reflectedlaser light exiting from the front of the skirt could escape when thelaser cutting head is in the position shown in FIG. 5. For example, ifangle A is approximately 30 degrees, and maximum distance D between thedoor 12 and the laser cutting head 8 is about 1.5 meters, the width W ofthe door is preferably about 830 mm. Advantageously, since angle A isrelative small (e.g., less than 60 degrees and preferably less than 40degrees), and the maximum distance between the laser head and the dooris relatively short (e.g., less than 3 meters), the door 12 can berelatively small. For example, the width W of door 12 may be less than 3meters, preferably less than 2 meters.

Preferably, the skirt 28 is small relative to the size of the protectivecover 14 within which it moves, and closely surrounds the laser cuttinghead 8. Referring now to FIGS. 3 and 4, the skirt 28 is preferablyformed of an array of pins 25 that extends downwardly from side legs 26of a U-shaped bracket 24. In this implementation, the bases 29 of thepins, which define the bottom of the skirt, are substantially level withthe tip of the nozzle 9 of laser cutting head 8. As a result, as shownin FIG. 6, when the nozzle 9 is positioned close to the workpiece 23during cutting, the bottom of the skirt will also be close to theworkpiece. For example, distance D between the bottom of the pins andthe upper surface of the workpiece may be less than 5 mm, preferablyabout 1 to 2 mm.

The pins 25 are arranged to form a labyrinth, i.e., by staggering therows of pins. This labyrinth arrangement prevents a reflected laser beam(which cannot turn a corner) from passing through the skirt 28. Theskirt is positioned relative to the laser nozzle so that the side arms30, 32 of the skirt protect the operator in side regions 20, 22 (FIG. 1)and the back 34 of the skirt protects the operator at the back of thelaser machine tool installation. As discussed above, the operator isprotected at the front of the installation by the protective door 12.

The pins, which may be made, for example, of brass, are mounted so thatthey can pivot freely with respect to the side legs 26. The pins may beof any desired length which will provide adequate light capture, forexample about 2 to 4 cm long. In some implementations, the pins arespring-mounted on the side legs 26, e.g., the pins 25 may include a pinbody 33 and a coil spring 35 disposed around an upper portion of the pinbody, as shown in FIG. 7. The freedom of movement of the pins preventsthe skirt from being damaged by movements of the workpiece; if theworkpiece tips during processing, the pins can deflect out of the waywithout damage.

The height of the base of the pins relative to the workpiece shouldgenerally be readily adjustable. When the laser is in operation, toprotect the operator the bases of the pins should generally be veryclose to the workpiece, e.g., a vertical distance of less than 5 mm,preferably 1 mm or less. To accomplish this, the array of pins ispreferably capable of being adjusted upward to accommodate workpieceshaving different thicknesses or non-uniform thickness. In someimplementations, this adjustment is provided by mounting the skirt ofpins to travel vertically with the laser head. Thus, in theimplementation shown in FIGS. 3 and 4, the U-shaped bracket 24 carryingthe pins is mounted on a Z-axis plate 21 of the motion unit 13, so thatthe skirt of pins will move vertically with the laser cutting head 8.

However, in some processes the laser nozzle may be turned on when it isa significant vertical distance from the workpiece, in which case theoperator could be exposed to reflected laser light if the bases of thepins were elevated at the level of the laser nozzle. Thus, in someimplementations the skirt of pins is mounted so as to move vertically(in the z direction) independently of the laser cutting head. The skirtof pins still travels with the laser cutting head in the x-y plane.

An example of an implementation in which the pins are mounted to movevertically independently of the laser cutting head is shown in FIG. 8.In this implementation, the pin bracket 45, carrying pins 46, is raisedand lowered by a motor 44, e.g., a motor with a Profibus controller. Themotor raises and lowers the pin bracket 45 through transmission belt 50which rotates cam 52, which is connected to the pin bracket 45 viaroller 54, brace 56 and guides 58. The cutting head 8, with nozzle 9, ismounted on a separate z-axis plate 2 which is movable independently ofthe pin bracket 45 by a z-axis drive (not shown).

When the bracket 45 and pins 46 are in an upper, reference position(e.g., 50 mm about the workpiece (z=0)), a reference switch 62 (in itsON position) indicates that the pin bracket 45 is in this upperposition. Initially, the nozzle 9 is also in a raised position, e.g., atz=105 mm. The distance between the vertical positions (in the zdirection) of the nozzle 9 and the pin bracket 45 is stored by thecontroller as a reference distance (RD).

When the cutting head is moved downward by the Z-axis plate 2, a switch60 turns to the ON position. Switch 62 first turns OFF (cam 66 movesaway.) The distance RD and the actual position of the Z-axis plate 2 arethen used to calculate the distance that the pin bracket 45 must move inorder to be sufficiently close to the workpiece 47. After thiscalculation has been made, the motor 44 lowers the pin bracket 45 untilthe bases 64 of pins 46 are very close to the workpiece 47, e.g., 1 to 2mm from the workpiece. Switch 62 turns ON, activated by cam 65, andswitch 60 turns ON, activated by cam 13. Two signals from switches 60and 62 in a down position are needed for safety. Generally, in thisposition the bases 64 of the pins will also be about 1 mm above thebottom of nozzle 9 (unless the nozzle 9 is positioned unusually highabove the workpiece during this first lowering step).

At this stage, in some implementations a height regulation feature isturned on. The height regulation feature includes one or more sensor(s)(not shown) that sense the z position of the top surface of workpiece47, and send a signal to the z-axis drive causing the z-axis plate 2 tomove as needed to maintain an appropriate distance between the cuttinghead and the workpiece during operation.

The height regulation feature may also be used to regulate the height ofthe pins, e.g., to accommodate differences in thickness of theworkpiece, or tipping of the workpiece during cutting. This isaccomplished by the sensors sending the same signal, indicating theposition of the top surface of the workpiece, to the controller of themotor 44.

During the cutting operation, the nozzle 9 may be raised above theworkpiece 47, for example up to 50 mm, for special cutting operations orfor other reasons. Because the pin bracket 45 is controlledindependently by motor 44, the pin bracket will stay in placeimmediately above the workpiece 47 to protect the operator. When thecutting operation is over, the motor 44 will return the pin bracket 45to its raised, reference position, allowing the workpiece 47 to beeasily removed.

Referring now to FIG. 9, in some implementations the laser cutting headis mounted on a double supported motion unit (often referred to as agantry mount), rather than being cantilevered out from a supportingsurface 100 as shown in FIG. 1. When a gantry mount is used, a motionunit 70 is mounted on a pair of rails 72, 74, that define a machineframe 76. A brace 78 is positioned at the front of the machine frame 76,connecting rails 72, 74. In this case, the skirt 28 is mounted on themotion unit 70, and a protective front panel 80 is mounted directly tothe laser cutting head 8 to protect the operator in the open front areaof the skirt 28. The protective front panel includes a door 82, similarto door 12 discussed above with reference to FIG. 1. As discussed above,the skirt 28 may be mounted to move in the z direction with the cuttinghead 8, or may be controlled by a separate drive to move independentlyof the cutting head.

Other embodiments are within the scope of the following claims.

For example, if the skirt is extended so that its arms extend the fulllength of travel of the laser cutting head, the skirt need not travelwith the laser cutting head in that direction (i.e., towards and awayfrom the protective door.)

1. A machine tool installation comprising: a laser cutting headconfigured to be movable in at least two dimensions; a workpiece supportconfigured to support a workpiece in operative relationship with thelaser cutting head; a skirt configured to surround the laser cuttinghead on three sides and intercept light that passes from the head and isreflected off of the workpiece or workpiece support; and a protectivecover positioned to intercept light that is reflected off of theworkpiece or workpiece support and is not intercepted by the skirt; theskirt and protective cover being configured to move laterally with thelaser cutting head.
 2. The machine tool installation of claim 1 whereinthe skirt is configured to move vertically with the cutting head.
 3. Themachine tool installation of claim 1 wherein the skirt is configured tomove vertically independently of the cutting head.
 4. The machine toolinstallation of claim 1 wherein the skirt is configured to movehorizontally, in a second direction orthogonal to said lateral movement,with the laser cutting head.
 5. The machine tool installation of claim 1wherein the skirt comprises an array of pins mounted on a substantiallyU-shaped bracket.
 6. The machine tool installation of claim 1 whereinthe protective cover includes a door.
 7. The machine tool installationof claim 1 wherein the protective cover defines open side and backregions.
 8. The machine tool installation of claim 1 further comprisinga motion device configured to move the protective cover and lasercutting head laterally.
 9. The machine tool installation of claim 1further comprising a support structure from which the protective coverand laser cutting head are cantilevered and along which the protectivecover and laser cutting head move laterally.
 10. The machine toolinstallation of claim 1 further comprising a controller configured tocontrol the vertical height of the skirt, and a height regulation devicecomprising a sensor configured to detect the vertical position of theworkpiece and transmit a signal to the controller.
 11. The machine toolinstallation of claim 1 wherein the laser cutting head is configured tobe movable in three dimensions.
 12. The machine tool installation ofclaim 1 wherein the protective cover is mounted directly on the lasercutting head.
 13. The machine tool installation of claim 3 furthercomprising a skirt drive motor and a cam arrangement configured to raiseand lower the skirt in response to input from the skirt drive motor. 14.The machine tool installation of claim 4 wherein the skirt is configuredto move within the protective cover, which is not configured formovement in the second direction.
 15. The machine tool installation ofclaim 5 wherein the pins are arranged in a labyrinth, with their longaxes extending generally parallel to the direction of light emitted bythe laser cutting head.
 16. The machine tool installation of claim 5wherein the pins are spring-mounted.
 17. The machine tool installationof claim 8 further comprising a pair of opposed rails between which themotion device is mounted and along which the motion device, protectivecover and laser cutting head move laterally.
 18. A moving enclosure fora machine tool installation including a laser cutting head configured tobe movable in at least two dimensions, the enclosure comprising: a skirtconfigured to surround the laser cutting head on three sides; a z-axismotion control unit, on which the skirt is mounted, configured toposition the skirt vertically relative to a workpiece to be machined;and a protective cover positioned to intercept reflected light from thelaser cutting head that is not intercepted by the skirt; the skirt andprotective cover being configured to move laterally with the lasercutting head.
 19. The moving enclosure of claim 18 wherein the skirtcomprises an array of pins mounted on a substantially U-shaped bracket.20. The moving enclosure of claim 18 wherein the skirt is configured tomove independently of the cutting head.
 21. The moving enclosure ofclaim 18 wherein the protective cover is mounted directly on the lasercutting head.